TDK conference 2022

PCV-3 is a virus newly discovered in 2016, belonging to the genus Circovirus and the family Circoviridae, and has been detected in swine farms in many countries around the world. The pathogenesis is not completely understood yet, but it has been associated with a number of clinical symptoms. The aim of our study was to assess the PCV-3 virus prevalence in large Hungarian swine herds from a survey with large sample size.

Between July 2020 and April 2022 blood samples from 18 Hungarian large swine herds were tested by quantitative PCR to detect the genome prevalence of PCV-3 virus. The 1408 blood samples were used for the detection by pool sampling method, in which the samples from 4-5 individuals were mixed in equal amounts and analysed by qPCR. The test results were analysed in 6 age groups from weaning to the end of the fattening period. Furthermore, the PVC-2 vaccination status of the selected farms, its effectiveness and impact on the possible PCV-3 infections were also analysed.

In 94% (17/18) of the surveyed swine farms, PCV-3 positive samples were found. This rate is much higher than the previous international findings. The prevalence of PCV-3 virus was 31% (89/273) for the pools tested. The presence of PCV-2 virus in samples was found in 50% (9/18) of the farms, and pools proved to be positive in 15% (43/273) of the cases. The co-infection rate was 7% (20/273), which is higher than the results reported in the scientific publications so far. Quantitative PCR analysis provided an opportunity to determine the degree of PCV-3 viral load. 24% of the results belonged to the low viral load group (Cq value >30), 6% to the medium viral load group (28

The study confirmed that PCV-3 is present in almost all the surveyed Hungarian swine farms. This finding greatly increases the importance of PCV-3 virus surveys in the future. The high viral load and co-infection rate raise the possibility of subclinical infection, but the severity of its consequences could only be confirmed by further research. The development of a combined vaccine against PCV-2 and PCV-3 could be a tool to achieve higher animal health status and welfare, which is an essential element of the profitable pig production.